3-Stage Application of SPC in FMECA
The application of SPC is done normally in three stages. These are briefed out here below:
The application of SPC commences with developing & understanding of the process, identifying the chief process parameters and defining the control mechanism available. The technique that is widely utilized during this initial diagnostic plan is failure mode, effect & criticality analysis (FMECA). This technique helps to recognize the critical characteristics of the process, which needs further more detailed analysis. A 'criticality' column is added to the analysis, to permits the inclusion of an index associated to the criticality of the failure effect. Sometimes as the criticality rating is omitted; the analysis is then FMEA.
The second stage involves the collection & analysis of the process data to determine what is normal variation. The procedure has to be bounded to include the inherent variability and to exclude the special causes of variation. Determination of normal variation needs a fundamental understanding of the process. The process data is also evaluated throughout this analysis phase to check whether the distribution is normal.
The 3rd stage in the application of SPC includes the analysis of the critical characteristics to resolve the relationship among the natural variation of the procedure and the allowable specification limits. At last, the ongoing control of the process might be monitored by using control charts.
Therefore we can notice that the use of FMEA represents the initial stage in the application of SPC. Thus, to apply SPC, it is necessary to have net understanding on the concept of FMEA/FMECA.